1. Field of the Invention
The present general inventive concept relates to a backlight system and a liquid crystal display using the same, and more particularly, to a direct light type of backlight system used in a liquid crystal display.
2. Description of the Related Art
A liquid crystal display (LCD), commonly known as one of the types of flat panel display devices, is a passive display that forms an image using incident light from an outside source as opposed to using self luminescence. A backlight system may be used in a LCD device and may be disposed at a rear portion of the LCD to irradiate light toward a liquid crystal panel.
Backlight systems are classified into two different types, a direct light type of backlight system and an edge light type of backlight system. In the direct light backlight system, light is emitted from a plurality of light sources disposed in back of a liquid crystal panel and is irradiated toward the liquid crystal panel. In the edge light type backlight system, light is emitted from a light source disposed on a sidewall of a light guide panel and is transmitted to the liquid crystal panel. The direct light type of backlight system may use a light emitting diode, which emits Lambertian light as a point light source.
Backlight systems use a diffusion plate for diffusing light emitted from a light source such that light is uniformly irradiated onto the liquid crystal panel.
In the case of the direct light type backlight system, which uses a light emitting diode as a light source, a transmission diffusion plate is disposed above the light source.
If the transmission diffusion plate is disposed too close to the light source, color of the light emitting diode used as a point light source appears as a spot from the light emitting diode.
Accordingly, in order to diffuse the light emitted from the light source more uniformly, it is necessary to increase a distance between the light source and the transmission diffusion plate, which results in an increase in the thickness of the backlight system.
However, when the backlight system is thick, an LCD employing such a backlight system, for instance, an LCD TV, is also thick, thus failing to satisfy a slim design requirement.
In the case of the direct light type backlight system, a plurality of light emitting diodes are arranged in two or more lines, with each line including a plurality of light emitting diodes. When a distance between the lines increases, an undesirable bright line appears. Accordingly, the distance between the lines should be kept sufficiently close such that the bright line does not appear.